APPLICANT'S ABSTRACT: While many studies have demonstrated the effectiveness of substance abuse treatment, research is sparse regarding substance abuse patients' medical conditions and patterns of pre-treatment medical services utilization as they impact medical services utilization and outcome. The proposed work for this K23 application examines pre-treatment medical services utilization, medical conditions and medications, and their impact on medical services utilization and outcome at one year as well as longer-term (7 year) trajectories. This application interacts with an NIAAA grant on a long-term follow-up of individuals admitted to an HMO's substance abuse treatment program; it addresses analyses not proposed in that application. The applicant, Charles Moore, M.D., M.B.A. is a clinician and subregional Chief of Mental Health and Substance Abuse Services for the HMO, and has been extensively involved in the original study. He has raised many of the questions that the research team has developed in the past few years. The conceptual model of the original grant--which examines individual factors, treatment characteristics, and extra-treatment factors among a sample of 1204 individuals who entered an HMO's substance abuse treatment program--is broadened here to include pretreatment medical utilization patterns and pretreatment medical conditions as they impact treatment retention, treatment outcome, medical utilization, and cost. The proposed work addresses such research questions as: What is the impact of individual characteristics (including type of pretreatment medical conditions), treatment and extra-treatment characteristics on "appropriate use" (i.e., outpatient, preventive health services)? Furthermore, is this impact dose related? It will also examine whether high pre-treatment utilization (inpatient and ER) and chronic co-morbid medical conditions are related to a) shorter stays in index treatment; and, b) rates of abstinence and numbers of days abstinent post-treatment. Kaiser Permanente has on-going computerized data to document the dates, diagnoses and settings of all health care utilization received and costs. The analysis will first focus on baseline and 12 month data. In the later years of the application, analysis will include the 5 year follow-up and longer-term utilization data, in close collaboration with the work of the larger study as well.